The manufacture of friction bands such as transmission bands for automatic vehicle transmissions and brake bands have been relatively expensive. The bands, which have an arcuate shape, comprise an outer metallic strip and an inner friction lining strip. A bracket is applied on each free end of the metallic strip for gripping of the band and tightening around a drum. The brackets have generally been welded to the metallic strip.
In the past, because of the high heat of welding, the metallic strips have first been formed into the arcuate shape desired and the brackets then welded onto the ends. The lining strip has then been adhered to the interior surface of the metallic strip. As will be appreciated, the process of adhering a lining strip to an arcuate metal band is time consuming and expensive. However, in order to avoid damage to the lining strip by the heat of welding, it has been necessary to adhere the lining strip at the last stage of the manufacture of the band.
In U.S. Pat. No. 3,581,380, over which the present invention constitutes an improvement, the lining strip was adhered to the metallic strip before the brackets were welded on. The adhering step was thus accomplished while the strips were flat straight elements and could be accomplished in a relatively inexpensive manner. The two adhered strips were then formed into the desired arcuate shapes and the brackets were welded onto the ends of the metallic strip. The method of welding involved placing one electrode directly against a bracket and placing another electrode against the side edges of the metallic strip for the flow of current between the two electrodes.
One problem with this type of welding is that prior to the welding step, it has been necessary to be sure that the edges of the metallic strip are uniform and that none of the friction material overlaps the edges of the metallic strip which requires additional manufacturing effort.
In accordance with the present invention, it has been learned that it is possible to provide sufficient exposed area of the outer surface of the metallic strip in the area of the brackets to permit closely adjacent contact of the electrodes against the brackets and outer surface of the metallic strip to result in substantially direct flow of current between the electrodes in the area of the desired weld. This minimizes inconsistencies which might occur in welding if the path of the current is not effectively controlled.